Choosing and Using Canning Lids
Artwork by Bethany Caskey
For canning food in jars, only lids designed for the purpose will provide a safe seal. Lids for home canning come in one of two diameters, depending on whether they fit narrow mouth jars or wide mouth jars. Narrow mouth lids, known as regular or standard lids, are 2 3/8-inch in diameter. Wide mouth lids are three inches in diameter. Both sizes are available as either single-use or reusable.
A single-use lid consists of a flat metal disk, plastic coated on the inside, with a plastic gasket bonded around the edge. The most common lids are plain metal, often with the manufacturer’s name printed on them. Sometimes they come in solid colors, or painted with attractive designs, intended for gift-giving.
When you buy jars new in the manufacturer’s box, they may come with a set of these lids, along with metal bands that screw onto the jars to hold the lids in place during processing. Once the original lids have been used, you will need to purchase new lids.
Both wide mouth and narrow mouth lids come in boxes of 12, with or without metal bands. While the lids are not intended for reuse, the bands may be washed, stored dry and used multiple times. Because this style of lid consists of a disk and a separate band, it is sometimes referred to as a two-piece canning lid.
All brands made in the United States, including Ball and Kerr, come from one company — Jarden (jardenhomebrands.com) — and are BPA free. Unused lids supposedly remain usable for about five years, after which the gasket may deteriorate, causing the seal to fail.
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To apply single-use lids, follow these steps:
1. Wash and rinse the lids, and set them aside on a clean towel.
2. After properly filling each jar, wipe the rim with a clean, damp paper towel.
3. Place the lid, gasket side down, on the cleaned rim.
4. Place a metal band over the lid and screw it down (see “How Tight Is Tight Enough?” on page 55).
5. Using a jar lifter, place the jar in the canner for processing.
During processing, two things happen: air escapes from the jar, and heat causes the gasket to soften. As the jar cools and its contents contract, a vaccuum forms and pulls the lid down and the gasket seals air-tight against the jar’s rim. When the seal is properly formed, the lid pulls down with a satisfying, “Pop!” Those of us who enjoy canning listen for the sound. It may occur as the jars are being removed from the canner, or it may not occur until the jars have been cooling awhile.
When a lid pops, the center becomes depressed. You therefore can tell a seal is tight if the lid is dished downward after the jar cools. The way food settles in the jar can be another clue, but one that takes experience to learn to recognize.
When a seal fails, it is most likely to occur as jars cool, giving you time to either reprocess the food or refrigerate it for immediate use. Occasionally a seal fails during storage, causing the food to spoil in the jar. Every canner needs to know the methods for testing a seal, as described under “Testing the Seal.”
Reusable lids consist of three pieces: a plastic disk, a separate rubber gasket, or ring, and a metal screw-on band. These lids are made by S&S Innovations and sold under the Tattler brand (reusablecanninglids.com). Commonly called Tattler lids, they are made in the United States, are BPA free, and are dishwasher safe. The lids are reusable as long as they remain undamaged. The rubber gaskets also may be reused unless they get cut or become stretched out of shape.
Tattler lids may be purchased in boxes of a dozen, or in bulk. The disks are typically white but are sometimes offered in solid colors. They come with the rubber rings, but not with screw-on metal bands, which are identical to those used for metal lids. Metal bands and replacement rings may be purchased separately.
Although Tattler lids are initially more expensive than single-use lids, being a one-time purchase makes them considerably cheaper in the long run. Exceptions would be if you are canning foods to give as gifts or offer at a farmers market, where the lids become unavailable for reuse.
Tattler lids are applied slightly differently from two-piece metal lids. If you are already using two-piece lids, the Tattler process takes a bit of getting used to. To apply a Tattler lid, follow these steps:
1. Wash and rinse lids and rings.
2. Place lids and rings in simmering water until you are ready to use them.
3. After properly filling each jar, wipe the rim with a clean, damp paper towel.
4. Place a ring and lid combination on the cleaned jar.
5. Place a metal band over the lid and screw it down (see “How Tight Is Tight Enough?” on page 55).
6. Using a jar lifter, place the jar in the canner for processing.
7. When the processing time is up, turn off the burner and let the canner cool for 10 minutes.
8. After the jars are removed from the canner and food stops bubbling in the jars, firmly tighten the bands to ensure a good seal.
As with a metal lid, vacuum pressure pulls a plastic lid against the rubber gasket to form a tight seal. After the jars cool and the bands are removed, you can tell each seal is tight by lifting upward on the lid. If a seal fails, the lid will come off the jar.
I’ve seen claims that Tattler lids won’t seal because the plastic disk lacks flexibility, which is nonsense — Weck canning jars, with their inflexible glass lids and reusable rubber gaskets — have been safely used in Europe since the late 1800s. Sealing jars with Tattler lids works much the same way as sealing Weck jars.
One-piece metal lids were once widely sold for home canning and still may be found. They are the same as metal lids used by commercial food processors that process food in glass jars. For home use, they are more popular for food storage than for food processing, for these reasons: you must make sure the lids are designed specifically for food processing; using them is slightly more complex than using multiple-piece lids; and once sealed, these lids can be difficult to remove intact.
They are, however, handy for use on jars that have been opened but the contents not immediately used up. Without one-piece lids, you’d be left fiddling with a lid and a band every time you wanted to refrigerate a partial jar of home canned food.
On the other hand, for food storage, metal one-piece lids have two disadvantages: they come only in the narrow mouth size and eventually they corrode. Plastic one-piece lids are available in both wide mouth and standard sizes. They may not be as appealing, but they are more durable and may be tossed in the dishwasher without concern for corrosion. Plastic one-piece lids are for food storage only; they cannot be used for processing hot jars.
CARE OF LIDS AND BANDS
With both two-piece lids and Tattler lids, after jars have cooled for at least 12 hours, the metal band should be removed before the jars are washed and stored. If the bands are left on the jars, you might not notice if a seal has failed. Further, bands left on jars tend to rust and become difficult to remove later. Washed, dried, and stored where they won’t get rusty or bent, the bands may be reused any number of times.
The typical way to open a jar sealed with a single-use metal lid is with a bottle opener. To avoid damaging a reusable Tattler lid or its rubber gasket, wedge a table knife between the gasket and the jar’s rim; do not use a sharp knife, or you risk cutting the gasket and rendering it no longer usable.
Before each canning session, examine your lids for damage, wash them in soapy water, and rinse them well. Check rubber gaskets to see that none is cut or stretched out of shape. Make sure screw-on bands are not rusty, bent, or warped. The bands need not be washed prior to reuse, provided they were stored clean.
METAL BAND — A metal ring that screws down over the threads of a canning jar to hold the lid in place during processing.
HEADSPACE — Empty space between the top of canned food in a jar and the jar’s rim.
NARROW MOUTH — A lid that fits canning jars with a 2-3/8 inch diameter mouth; also called standard.
TATTLER LID — A three-piece canning lid consisting of a plastic disk and rubber ring, held in place with a metal screw-on band.
TWO-PIECE CANNING LID — A canning lid consisting of a metal disk bonded to a gasket and held with a metal screw-on band.
WECK JARS — Canning jars with rubber rings and glass lids, widely used in Europe.
WIDE MOUTH — A lid that fits a canning jar with a three-inch diameter mouth.
HOW TIGHT IS TIGHT ENOUGH?
A cause of anxiety for many home canners is learning to screw metal bands onto jars with just the right amount of tension. Whether you use two-piece lids or three-piece Tattler lids, tension is usually described as “fingertip tight.” A helpful way to learn correct tension is to practice with an empty jar.
Place the jar on the counter. Place a lid on the jar. With one finger in the center of the lid for stability, use the other hand to screw down the band just to the point of resistance, which is when the jar itself starts to turn. The band is now “fingertip tight.” If you do the same thing with water in the jar to within an inch of the top, then turn the jar sideways, a “fingertip tight” seal will prevent water from leaking out of the jar.
When tightening the band on a metal lid, turn the band until you feel resistance. Then, without using force to crank the band tight, slightly snug down the band by turning it one-quarter inch more. Some canners use Ball’s Sure Tight band tool—essentially a torque wrench for canning jars—that is designed to secure bands with precisely the right amount of torque. After the jars come out of the canner, do not retighten the bands or you will risk breaking the seal.
When tightening the band on a Tattler lid, turn the band just to the point of resistance, and then stop. After the jars come out of the canner, and food has stopped bubbling in the jars, retighten the bands to ensure a good seal. Some canners like to use a jar wrench to tighten hot bands and to loosen sticky bands after the jars cool.
TESTING THE SEAL
Always test each jar for a sound seal after processed jars have cooled for at least 12 hours and the metal bands have been removed. For Tattler lids, use the first method; for two-piece lids, use any or all of the following methods.
• Grasp the edge of the lid and lift upward. If a seal fails, the lid will lift off the jar.
• Press the middle of the lid with your finger. A failed seal either pops down or springs back up, and in doing so may make a popping sound.
• Tap the lid with the tip of your fingernail or the bottom of a spoon. A good seal makes a pleasant ringing sound; a failed seal makes a dull thud. (Note that food touching the bottom of the lid can also cause a thud.)
• With the top of the jar at eye level, check to see if the lid is flat or bulging upward. A good seal curves slightly downward.
A common cause of failed seals is food residue between the jar’s rim and the lid. Food residue may come from overfilling a jar (leaving too little headspace), or from not carefully wiping the jar’s rim before applying the lid. It may also come from not screwing the band down tight enough, allowing liquid to leak out of the jar during processing. On the other hand, a ring that’s screwed down too tight won’t allow air to vent from the jar, which can also cause a failed seal and may cause the jar to break during processing.